The present invention relates to a method for providing a low-molecular radical, more particularly, a method for generating a low-molecular radical and a radical-carrying molecule from a super-stable perfluoroalkyl-based radical generated from the above radical-carrying molecule.
A radical is generated from a radical initiator by heating or irradiating the same in the polymer synthesis, for example, and is utilized. A conventional radical initiator cannot be used as a radical initiator again once it is decomposed to generate a radical.
Among radical initiators, U.S. Pat. No. 2,559,630 discloses bis(perfluoroacyl) peroxide as a fluorine-based radical initiator generating a perfluoroalkyl radical, and N-trifluoromethyl-N-nitrosotrifluoromethanesulfonamide and the like are known (T. Uemoto and A. Ando, Bull. Chem. Soc. Jpn., 59, 447-452(1986)).
As the fluorine-based radical initiator, Japanese Kokoku Publication Hei-1-29175 suggests the utilization of perfluoro(2,4-dimethyl-3-isopropyl-2-pentene), which has an extremely high chemical stability, with an ethylenically unsaturated monomer such as tetrafluoroethylene or chlorfluoroethylene in an aqueous or non-aqueous system.
Such an extremely high stability of perfluoro(2,4-dimethyl-3-isopropyl-2-pentene) is also disclosed in U.S. Pat. No. 4,626,608 and K. V. Scherer, T. Ono, K. Yamanouchi, R. Fernandez, P. Henderson, J. Am. Chem. Soc., 107, 718-719 (1985).
However, the method for re-generating the super-stable perfluoroalkyl-based radical and releasing the reactive radical after releasing a reactive radical having a lower molecular weight from such a super-stable perfluoroalkyl-based radical having an extremely high chemical stability has not been disclosed.
Since such a perfluoroalkyl radical generating reagent is expensive, the development of a radical providing method which allows the same to be utilized repetitively as a radical generator even after generating a radical has been desired. Especially in these years, environmental consciousness emphasizes xe2x80x9catom economyxe2x80x9d and xe2x80x9cgreen chemistryxe2x80x9d and leads to an increased demand of the development of the radical providing method as described above.
In view of the above-mentioned state of the art, it is an objective of the present invention to provide a method for providing a low-molecular radical which comprises releasing a radical having a lower molecular weight from a super-stable perfluoroalkyl-based radical followed by generating the above super-stable perfluoroalkyl-based radical.
The invention is a method for providing a low-molecular radical which comprises a super-stable radical generating reaction for generating a super-stable perfluoroalkyl-based radical from a radical-carrying molecule and a radical releasing reaction for releasing the low-molecular radical from said super-stable perfluoroalkyl-based radical, said radical-carrying molecule being generated as a result of said-radical releasing reaction.
The invention is a radical-carrying molecule which is used in the above method for providing the low-molecular radical.
The invention is a process for polymerization which comprises using the low-molecular radical released by the method for providing the above low-molecular radical as a polymerization initiator.